1. Field of the Invention
The present invention relates to a board-to-board coaxial connector which electrically connects two printed circuit boards with each other in various electronic apparatuses such as a communication apparatus or a computer.
2. Description of the Prior Art
In various electronic apparatuses such as a communication apparatus or a computer, in order to realize transmission of a high-frequency signal between two printed circuit boards which are placed in substantially parallel to each other, conventionally, a method has been employed in which coaxial connector receptacles are surface mounted on the printed circuit boards, respectively, and the receptacles are connected by a coaxial jumper cable of a predetermined length having L-type coaxial connector plugs. The connector plugs are disposed at the both ends, and fittable to the coaxial connector receptacles, respectively. However, the method has defects such as that the number of parts is large, that a space for housing the jumper cable must be assured, and that a fitting work must be conducted on the two sets of coaxial connector pairs.
Board-to-board coaxial connectors for, without using a jumper cable, electrically connecting two printed circuit boards which are placed in substantially parallel to each other have been proposed. For example, Japanese Patent Application Laying-Open No. 6-314580 discloses a coaxial connector consisting of a male connector and a female connector. The male connector is fixed by surface mounting a leg of a male terminal pressingly inserted into a housing, onto a grounding conductor of one circuit board. By contrast, the female connector is fixed by surface mounting a leg portion of a female terminal pressingly inserted into a housing, onto a grounding conductor of another circuit board. The connectors are fitted with each other. A conductive screw is inserted from a bolt insertion hole of the one circuit board, passed through a middle portion of the coaxial connector, and then screwed with a screw hole of the other circuit board to be fixed thereto. A head portion of the conductive screw is in press contact with a signal conductor of the one circuit board, and an external thread portion of the conductive screw is in contact with an internal thread portion which is electrically continuous to a signal conductor of the other circuit board, so that the conductive screw serving as a center conductor electrically connects together the signal conductors of the circuit boards. Japanese Patent Application Laying-Open No. 8-236227 discloses another coaxial connector consisting of: a spring type contact pin which is held by an insulation holder, and in which a contact terminal in a basal end portion is connected to a signal circuit of one circuit board, and an end portion of the contact pin in a tip end portion is elastically contacted with a signal circuit of another circuit board in the axial direction of the connector; and a spring type contact plug which is held by an insulation holder so as to surround the spring type contact pin, and in which a contact terminal in a basal end portion is connected and fixed to a ground circuit of the one circuit board, and an end portion of the contact plug in a tip end portion is elastically contacted with a ground circuit of the other circuit board in the axial direction of the connector. International Patent Publication No. 2001-518231 discloses a coaxial connector having a first connector and a second connector. The first connector has an internal contact in which the tip end butts directly against an internal circuit trace of another circuit board in the axial direction of the connector, and which is elastically movable in the axial direction. The second connector has an external conductor which is surface mounted and fixed onto an external circuit trace of the other circuit board to be fittingly connected to an external connector of the first connector.